570. Epidemiology of Influenza Hospitalizations in Children with Acute Lymphoblastic Leukemia (ALL), 1999 2011
Session: Oral Abstract Session: Immunization of Children and Adults with Immune Deficiencies
Thursday, October 3, 2013: 2:00 PM
Room: The Moscone Center: 250-262
Background:

Immunosuppression after chemotherapy is a risk factor for severe influenza. Data are lacking regarding influenza burden and outcomes in pediatric cancer populations. We described the epidemiology of influenza hospitalizations in children with new-onset ALL.

Methods:

We performed a retrospective longitudinal study of 10,698 new-onset ALL subjects 0 – 19 years of age between 1999 – 2011 using the Pediatric Health Information System, a resource utilization and billing database from 43 freestanding U.S. children’s hospitals.  Seasonal influenza hospitalizations (SI) were identified using discharge diagnosis codes for influenza. Hospitalizations during low influenza prevalence periods were excluded.  Community-onset influenza hospitalizations (CO-I) required additional influenza testing within two days of admission; repeat admissions were excluded. Follow-up was censored at the earliest of four events: 1) September 30, 2011, 2) expected end of chemotherapy, 3) last known admission or 4) hematopoietic stem cell transplant. Incidence calculations were adjusted for season-specific person-time. Crude attributable mortality was calculated using baseline mortality for non-influenza admissions.

Results:

Overall SI crude attributable mortality was 1.1% (Table). There were no deaths amongst CO-I. Median length of stay for SI and CO-I was 5 days (IQR 3-8) and 4 days (IQR 3-6), respectively. 10.7% of SI and 5.1% of CO-I required intensive care.

Table:  Incidence & Attributable Mortality of Influenza Hospitalizations in Pediatric ALL

 

All Seasonal Influenza

(n=590)

Community-Onset Influenza

(n=218)

 

Incidence* 

(95%CI)

Case-Fatality

(95% CI)

Crude Attributable Mortality

Incidence *

(95% CI)

Overall

578.9

(533.1 – 627.5)

1.53%

(0.70 – 2.90)

1.1%

213.9

(186.4 – 244.3)

Age Category

 

0 to < 2 years

706.7

(461.6 – 1,035.4)

7.69%

(0.93 – 27.79)

6.98%

244.6

(111.9 – 464.4)

2 to < 5 years

627.0

(546.7 – 715.8)

1.37%

(0.28 – 4.00)

1.17%

223.3

(176.5 – 278.7)

> 5 years

544.9

(488.9 – 605.6)

1.16%

(0.32 – 2.97)

0.63%

206.9

(180.8 – 245.5)

Time from ALL Diagnosis

 

< 6 Months

544.4

(470.3 – 626.9)

2.07%

(0.56 – 5.31)

1.70%

155.1

(116.9 – 201.9)

> 6 Months

597.3

(540.0 – 659.0)

1.26%

(0.41 – 2.94)

0.65%

245.2

(209.0 – 285.9)

* Incident influenza admissions per 100,000 person-months

Conclusion:

Children with ALL experience a substantial hospitalization burden due to influenza; however, attributable mortality is low.

Grace E. Lee, MD1,2, Brian Fisher, DO, MPH, MSCE1,2, Yuan-Shung Huang, MS1, Yimei Li, PhD1, Alix Seif, MD, MPH1, Rui Xiao, PhD2 and Richard Aplenc, MD, PhD1,2, (1)The Children's Hospital of Philadelphia, Philadelphia, PA, (2)Center for Clinical Epidemiology & Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA

Disclosures:

G. E. Lee, None

B. Fisher, None

Y. S. Huang, None

Y. Li, None

A. Seif, None

R. Xiao, None

R. Aplenc, None

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